1. Field of the Invention
The present invention relates to a magnetic transfer apparatus for use in performing magnetic transfer from a master carrier having patterns corresponding to transfer information to a slave medium having a magnetic recording part, and in particular, to a magnetic transfer apparatus capable of accurately feeding the slave medium to the master carrier held in a holder.
2. Description of the Prior Art
Generally, a master carrier (patterned master) for magnetic transfer comprises transfer patterns such as servo signals in the form of surface irregularities or embedded structure, with at least a soft magnetic layer on a surface layer. Such a master carrier comes into close contact with a slave medium having a magnetic recording part, and a magnetic field for transfer is applied, whereby magnetic patterns corresponding to information carried on the master carrier are transferred to and recorded on the slave medium. Such technologies are disclosed in Japanese Patent Laid-open Publication No. Sho. 63-183623 and Nos. Hei. 10-40544 and 10-269566, and Japanese Patent Laid-open Publication No. 2001-256644 and like.
In cases where the slave medium is a disk-shaped magnetic recording medium such as a hard disk or high-density flexible disk, a transfer magnetic field is applied by a magnetic field application unit including an electromagnet device or permanent magnet device which is disposed at one side or both sides of the slave medium, in a state that a disk-shaped master carrier is kept in close contact with the slave medium.
As an important condition upon performing magnetic transfer, there is positioning of the master carrier and the slave medium with high accuracy. Particularly, in the slave medium such as a hard disk or high-density flexible disk, a rotation center thereof when being attached to a drive unit after magnetic transfer should be accurately aligned with a center of a recorded magnetic pattern.
In this regard, Japanese Patent Laid-open Publication No. Hei. 11-175973 and Japanese Patent Laid-open Publication No. 2001-209978 disclose a positioning process of a master carrier and a slave medium by use of an imaging unit when the slave medium comes into close contact with the master carrier. Specifically, the slave medium is set to a close contact flange, on which the master carrier having markers formed with transparent portions corresponding to patterns is placed. Then, while positions of the markers and the slave medium are observed by use of the image unit to be aligned, the master carrier is correctly positioned and comes into close contact with the slave medium. Alternatively, the master carrier may be set into the holder capable of moving in an X-Y direction, and may be brought into close contact with the slave medium after aligning them while being observed the center position thereof by use of a CCD camera.
Thus, there is proposed, by the present inventors, a technique of positioning a slave medium and a master carrier with high accuracy by previously positioning a center of transfer patterns of the master carrier relative to a center of a slave holding shaft (center pin) of the holder, and then positioning the slave medium by the slave holding shaft (Japanese Patent Application No. 2001-302231).
Meanwhile, the slave medium and the master carrier are set into the holder by horizontally conveying the slave medium onto the master carrier to be superimposed in up and down directions, or by vertically conveying the slave medium at any one side of the master carrier for perpendicular arrangement. However, the latter case of vertically conveying the slave medium suffers from the disadvantages such as dropping of the slave medium during conveyance, and penetration of dust into a gap between the contact surfaces of the slave medium and the master carrier in addition to above-mentioned positioning. Thus, it is preferable that the slave medium is fed while being held by a slave-feeding unit.
As such, in order to ensure the high quality of signal recording parts of the slave medium, any portion except for the signal recording parts of the slave medium should be held by the slave-feeding unit.
Meanwhile, in order to hold the slave medium in the holder during performing magnetic transfer, an inner diameter portion of a central opening of the slave medium is supported by use of the slave holding shaft. However, since the central opening of the slave medium is only hung around the slave holding shaft until being compressed upon transfer, the slave medium may be detached from the slave holding shaft due to vibration during handling. In addition, since a gap may be formed between the master carrier and the slave medium, environmental dust may be attached to the close contact surfaces of the master carrier and the slave medium to cause deterioration of transfer quality. Further, in the state of being tilted, an edge of the master carrier or the slave medium partially comes into strong contact with the slave medium or the master carrier during being compressed, thus damaging the slave medium or the master carrier, and causing poor transfer.